embassy/embassy-stm32/src/pwm/complementary_pwm.rs

use core::marker::PhantomData;

use embassy_hal_common::{into_ref, PeripheralRef};
use stm32_metapac::timer::vals::Ckd;

use super::simple_pwm::*;
use super::*;
#[allow(unused_imports)]
use crate::gpio::sealed::{AFType, Pin};
use crate::gpio::AnyPin;
use crate::time::Hertz;
use crate::Peripheral;

pub struct ComplementaryPwmPin<'d, Perip, Channel> {
    _pin: PeripheralRef<'d, AnyPin>,
    phantom: PhantomData<(Perip, Channel)>,
}

macro_rules! complementary_channel_impl {
    ($new_chx:ident, $channel:ident, $pin_trait:ident, $complementary_pin_trait:ident) => {
        impl<'d, Perip: CaptureCompare16bitInstance> ComplementaryPwmPin<'d, Perip, $channel> {
            pub fn $new_chx(pin: impl Peripheral<P = impl $complementary_pin_trait<Perip>> + 'd) -> Self {
                into_ref!(pin);
                critical_section::with(|_| {
                    pin.set_low();
                    pin.set_as_af(pin.af_num(), AFType::OutputPushPull);
                    #[cfg(gpio_v2)]
                    pin.set_speed(crate::gpio::Speed::VeryHigh);
                });
                ComplementaryPwmPin {
                    _pin: pin.map_into(),
                    phantom: PhantomData,
                }
            }
        }
    };
}

complementary_channel_impl!(new_ch1, Ch1, Channel1Pin, Channel1ComplementaryPin);
complementary_channel_impl!(new_ch2, Ch2, Channel2Pin, Channel2ComplementaryPin);
complementary_channel_impl!(new_ch3, Ch3, Channel3Pin, Channel3ComplementaryPin);
complementary_channel_impl!(new_ch4, Ch4, Channel4Pin, Channel4ComplementaryPin);

pub struct ComplementaryPwm<'d, T> {
    inner: PeripheralRef<'d, T>,
}

impl<'d, T: ComplementaryCaptureCompare16bitInstance> ComplementaryPwm<'d, T> {
    pub fn new(
        tim: impl Peripheral<P = T> + 'd,
        _ch1: Option<PwmPin<'d, T, Ch1>>,
        _ch1n: Option<ComplementaryPwmPin<'d, T, Ch1>>,
        _ch2: Option<PwmPin<'d, T, Ch2>>,
        _ch2n: Option<ComplementaryPwmPin<'d, T, Ch2>>,
        _ch3: Option<PwmPin<'d, T, Ch3>>,
        _ch3n: Option<ComplementaryPwmPin<'d, T, Ch3>>,
        _ch4: Option<PwmPin<'d, T, Ch4>>,
        _ch4n: Option<ComplementaryPwmPin<'d, T, Ch4>>,
        freq: Hertz,
    ) -> Self {
        Self::new_inner(tim, freq)
    }

    fn new_inner(tim: impl Peripheral<P = T> + 'd, freq: Hertz) -> Self {
        into_ref!(tim);

        T::enable();
        <T as crate::rcc::sealed::RccPeripheral>::reset();

        let mut this = Self { inner: tim };

        this.inner.set_frequency(freq);
        this.inner.start();

        this.inner.enable_outputs(true);

        this.inner
            .set_output_compare_mode(Channel::Ch1, OutputCompareMode::PwmMode1);
        this.inner
            .set_output_compare_mode(Channel::Ch2, OutputCompareMode::PwmMode1);
        this.inner
            .set_output_compare_mode(Channel::Ch3, OutputCompareMode::PwmMode1);
        this.inner
            .set_output_compare_mode(Channel::Ch4, OutputCompareMode::PwmMode1);
        this
    }

    pub fn enable(&mut self, channel: Channel) {
        self.inner.enable_channel(channel, true);
        self.inner.enable_complementary_channel(channel, true);
    }

    pub fn disable(&mut self, channel: Channel) {
        self.inner.enable_complementary_channel(channel, false);
        self.inner.enable_channel(channel, false);
    }

    pub fn set_freq(&mut self, freq: Hertz) {
        self.inner.set_frequency(freq);
    }

    pub fn get_max_duty(&self) -> u16 {
        self.inner.get_max_compare_value()
    }

    pub fn set_duty(&mut self, channel: Channel, duty: u16) {
        assert!(duty < self.get_max_duty());
        self.inner.set_compare_value(channel, duty)
    }

    /// Set the dead time as a proportion of max_duty
    pub fn set_dead_time(&mut self, value: u16) {
        let (ckd, value) = compute_dead_time_value(value);

        self.inner.set_dead_time_clock_division(ckd);
        self.inner.set_dead_time_value(value);
    }
}

fn compute_dead_time_value(value: u16) -> (Ckd, u8) {
    /*
        Dead-time = T_clk * T_dts * T_dtg

        T_dts:
        This bit-field indicates the division ratio between the timer clock (CK_INT) frequency and the
        dead-time and sampling clock (tDTS)used by the dead-time generators and the digital filters
        (ETR, TIx),
        00: tDTS=tCK_INT
        01: tDTS=2*tCK_INT
        10: tDTS=4*tCK_INT

        T_dtg:
        This bit-field defines the duration of the dead-time inserted between the complementary
        outputs. DT correspond to this duration.
        DTG[7:5]=0xx => DT=DTG[7:0]x tdtg with tdtg=tDTS.
        DTG[7:5]=10x => DT=(64+DTG[5:0])xtdtg with Tdtg=2xtDTS.
        DTG[7:5]=110 => DT=(32+DTG[4:0])xtdtg with Tdtg=8xtDTS.
        DTG[7:5]=111 => DT=(32+DTG[4:0])xtdtg with Tdtg=16xtDTS.
        Example if TDTS=125ns (8MHz), dead-time possible values are:
        0 to 15875 ns by 125 ns steps,
        16 us to 31750 ns by 250 ns steps,
        32 us to 63us by 1 us steps,
        64 us to 126 us by 2 us steps
    */

    let mut error = u16::MAX;
    let mut ckd = Ckd::DIV1;
    let mut bits = 0u8;

    for this_ckd in [Ckd::DIV1, Ckd::DIV2, Ckd::DIV4] {
        let outdiv = match this_ckd {
            Ckd::DIV1 => 1,
            Ckd::DIV2 => 2,
            Ckd::DIV4 => 4,
            _ => unreachable!(),
        };

        // 127
        // 128
        // ..
        // 254
        // 256
        // ..
        // 504
        // 512
        // ..
        // 1008

        let target = value / outdiv;
        let (these_bits, result) = if target < 128 {
            (target as u8, target)
        } else if target < 255 {
            (64 + (target / 2) as u8, (target - target % 2))
        } else if target < 508 {
            (32 + (target / 8) as u8, (target - target % 8))
        } else if target < 1008 {
            (32 + (target / 16) as u8, (target - target % 16))
        } else {
            (u8::MAX, 1008)
        };

        let this_error = value.abs_diff(result * outdiv);
        if error > this_error {
            ckd = this_ckd;
            bits = these_bits;
            error = this_error;
        }

        match error {
            0 => break,
            _ => {}
        }
    }

    (ckd, bits)
}

#[cfg(test)]
mod tests {
    use super::{compute_dead_time_value, Ckd};

    #[test]
    fn test_compute_dead_time_value() {
        struct TestRun {
            value: u16,
            ckd: Ckd,
            bits: u8,
        }

        let fn_results = [
            TestRun {
                value: 1,
                ckd: Ckd::DIV1,
                bits: 1,
            },
            TestRun {
                value: 125,
                ckd: Ckd::DIV1,
                bits: 125,
            },
            TestRun {
                value: 245,
                ckd: Ckd::DIV1,
                bits: 64 + 245 / 2,
            },
            TestRun {
                value: 255,
                ckd: Ckd::DIV2,
                bits: 127,
            },
            TestRun {
                value: 400,
                ckd: Ckd::DIV1,
                bits: 32 + (400u16 / 8) as u8,
            },
            TestRun {
                value: 600,
                ckd: Ckd::DIV4,
                bits: 64 + (600u16 / 8) as u8,
            },
        ];

        for test_run in fn_results {
            let (ckd, bits) = compute_dead_time_value(test_run.value);

            assert_eq!(ckd.0, test_run.ckd.0);
            assert_eq!(bits, test_run.bits);
        }
    }
}